Syn. Spanish Flies.

The proper place for considering the subject of cantharides generally, will be among the epispastics. I shall here confine myself to its effects and uses as an internal medicine.

Effects on the System

Cantharides* is a powerful local irritant, and a general stimulant to the circulation, with a peculiar disposition to act on the urinary organs, and the pelvic viscera generally. in regard to its topical effects and uses, I shall treat of it with the epispastics. in this place, we are concerned with it only as an internal remedy. in observing the operation of cantharides, we may distinguish two sets of symptoms mingled together; those, namely, which result from its direct action on the alimentary mucous membrane, and those which follow its absorption. The reader will have no difficulty in discriminating between these two categories, in the general picture of its effects which follows.

* it will be noticed that I use the term cantharides, as having been adopted into the English language as a name for the medicine; and, in this capacity, there is an obvious convenience in considering it as in the singular number.

When given in moderate doses, it produces no obvious impression for some time, unless perhaps a feeling of warmth in the throat and stomach; but, after a few repetitions of the dose, a sense of heat or uneasiness is felt in the urethra, with a disposition to micturate more frequently than in health, some increase in the quantity of urine, and perhaps a slight excitation of the genital organs. With a longer continuance of the medicine, or an increase of the dose, these phenomena become much more prominent. There is now a constant disposition to pass the urine, which, instead of being increased in quantity, is often much diminished, coming away in a few drops at each effort, and often very highly coloured, or bloody. Severe burning or cutting pain accompanies the discharge; there is a constant uneasiness in the course of the urinary passages; and not unfrequently violent pains are experienced in the small of the back, in the groin, and down the thighs. Dr. Morel-Lavallee has ascertained that the urine, under these circumstances, contains albumen, and that portions of false membrane are sometimes discharged along with it. (Arch. Gén., 5e sér., viii. 533.) The rectum is sometimes involved, and the sufferings of severe tenesmus are added to those of strangury. The irritation, moreover, often extends to the genitals, and painful priapism, with other corresponding phenomena, is induced. Occasionally, too, there is more or less diaphoresis. With these local phenomena, the pulse is rendered more frequent and tense, the skin hot, the breathing hurried, anorexia comes on, more or less nervous disturbance is experienced, and a general febrile condition is established. These phenomena may be rapidly produced by over-doses; but they may all occur from a frequent and continued repetition of the ordinary remedial doses. Beyond these effects, the operation of the medicine may be considered as poisonous.

Poisonous Effects

The phenomena produced by poisonous quantities of cantharides are burning pain in the stomach, nausea and vomiting, thirst, dryness and constriction of the throat with difficult deglutition, sometimes ptyalism, fetid smell of the breath, violent gripings, tenesmus, bloody stools, exquisite tenderness of the abdomen, excruciating pains in the small of the back, loins, and hypogastric region, incessant disposition to micturate with the discharge of a few drops of blood, intense and durable priapism, violent uterine irritation in women, with occasional abortion in pregnancy, and inflammation more or less extensive of the urinary and genital apparatus, sometimes attended with gangrene. At first there is general excitement of the circulatory system; but, after a time, the system sinks, and faintness, feeble pulse, coldness of the surface, general sweats, giddiness, headache, delirium sometimes furious, convulsions of a tetanic character, and coma ensue. Death takes place, in some cases, from the intensity of the inflammation with the consequent gangrene; in others, apparently from the poisonous action upon the brain. A fatal result, according to Orfila, has taken place from 24 grains of the powdered flies; and very threatening symptoms are known to have ensued from a fluidounce of the tincture. From the experiments of Professor Schroff, of Vienna, upon rabbits, it appears that the fixed oils, given along with cantharides, hasten its fatal effects. (B. and F. Medico-chirurg. Rev., April, 1856, Am. ed., p. 407.) Upon dissection, the marks of inflammation, and sometimes of gangrene are to be seen in the mucous membrane of the stomach and bowels, and in that of the urinary and genital organs, and of congestion in the brain.

Treatment of the Poisoning. This consists in the evacuation of the cantharides by emetics and cathartics; with the free use of demulcent drinks; opiates by the mouth and rectum; and measures calculated to obviate inflammation, as bleeding, leeching, emollients, the warm bath, blistering, and the antiphlogistic regimen; care being taken to obviate prostration by a due amount of nutriment.

Mode of Operating

The symptoms of gastric and intestinal irritation or inflammation are probably mainly due to the direct action of the poison as swallowed; those exhibited in the urino-genital apparatus, and the nervous system, upon its influence after absorption. This influence, though universally irritant, is directed especially to the urinary and genital organs, and the whole contents of the pelvis, including the rectum; and a proof of this is that the same effects are often produced by the external application of the flies, though seldom to so serious an extent. it is uncertain whether the nervous symptoms are owing to the direct influence of the absorbed poison upon the nervous centres, or to the reaction upon these of the inflammation in the alimentary canal, and urino-genital apparatus. in favour of the latter opinion is the circumstance, that they generally do not make their appearance until some time after the others, occasionally not until several days subsequent to the introduction of the poison.

There is very great difference of susceptibility, in different individuals, to the influence of cantharides, and especially in relation to its effects on the urinary organs. in some, strangury is always induced by very small doses; in others, large quantities may be taken without the slightest effect of the kind.

Therapeutic Application

Cantharides was employed habitually by the ancient Greek and Roman physicians. As a therapeutic agent, it is now mainly used in reference to its influence on the urinary and genital organs.

In dropsy, it is asserted to have been occasionally given with advantage as a diuretic; but its operation in this way is too uncertain to be relied on under any circumstances, and, in many cases, particularly those of a febrile nature, and attended with active congestion or inflammation of the kidneys, it is positively, and very strongly contraindicated. The only circumstances, under which it would be appropriate in dropsy, are when there is great torpor of the kidneys, without the least evidence of vascular excitement in the organ; and even then it should be used cautiously, and only in conjunction with more decided diuretics.

Its most beneficial application is to paralytic or very debilitated states of the urino-genital apparatus, in which it is often useful. it may be employed, in all these cases, when the affection is local and functional, or when, supposing it to have arisen from inflammation in the parts, or from lesions of the nervous centres, there is reason to believe that the original cause has ceased to act, and nothing but the debility or inability remains. The special affections are the same as those already mentioned under oil of turpentine (see page 628); namely, retention and incontinence of urine, the former dependent on paralysis or weakness of the muscular coat of the bladder, the latter on the same condition of the sphincters; nocturnal incontinence, in which it is among the most efficient remedies; paralysis of the sphincter of the rectum or of the rectum itself; obstinate gleet and leucorrhoea; long - continued cystirrhoea; some cases of spermatorrhoea, purely the result of debility; impotence and sterility; and amenorrhoea. .

It has been used with asserted advantage in diabetes; but in the true disease of that name, characterized by saccharine urine, it is wholly useless if not injurious. in certain cases, however, of simple excessive diuresis, it may prove useful, like the oil of turpentine, when the affection is purely functional, and especially when connected with a relaxed or atonic state of the kidneys.

It is supposed, when circulating through the tissues, to be capable of exercising an excitant and alterative influence upon their ultimate structure, so as to prove useful in certain very obstinate local affections, by changing the nature of the diseased action. Hence it has been recommended internally in old and indolent ulcers, and especially in obstinate cutaneous eruptions. in the latter it appears to have been employed by the ancients, and, in recent times, has been again brought into notice by M. Biett, who has used it with great success. The cases to which it is applicable are the scaly affections, as psoriasis and lepra, and eczema and impetigo in their most advanced and scaly stage. But these are the very affections in which arsenic, in small and perfectly safe doses, operates usually with great effect, and without the unpleasant symptoms so apt to result from cantharides; so that the latter is comparatively little used.

Cantharides is among the substances which have been employed as prophylactics against hydrophobia; but the reader need scarcely be informed that, in the present state of our knowledge, it would be altogether unjustifiable to rely on its efficiency.

The dose of cantharides is from half a grain to two grains, which may be given morning and evening, in the form of pill. The tincture, however, is always preferable, as it does not, like the fly in substance, come undiluted in contact with the coats of the stomach. The dose of it is from fifteen minims to a fluidrachm; the latter quantity containing the strength of nearly two grains of the medicine, when the tincture is prepared according to the U. S. officinal directions. it should be given in a wineglassful of water, or some demulcent liquid.

There are a few other substances, of minor importance, which belong to the stimulant division of the diuretics. Of these, horse-radish, mustard, and garlic merit a brief notice.